Winni Tide

[SAMIAM]

Did you know that large lakes have a tiny tide,just as the oceans do?.Studies by the University of New Hampshire Maritime Club have shown that Alton Bay and Center Harbor each have a 3" fluctuation that coincides perfectly with the tide charts for the Prtsmouth area.Just a little trivia to keep everyone occupied until we get some snow.

[gtxrider]

Ah, the cause of the big waves has been solved.

It appears that there is snow on SNAKE EYES or just a heavy fog.

[Island Girl]

I am betting it is snowing on Rattlesnake Island right now. That is the view in a very heavy rainstorm, so it is probably the same or more dense when it is snowing.

Let's hope the wind dies down so the lake can freeze soon.

[Merrymeeting]

Originally Posted by Island Girl

Let's hope the wind dies down so the lake can freeze soon.

We're a weird breed aren't we? We spend a good part of December wishing/hoping the lake will hurry up and freeze. Then watch anxiously in March for it to thaw!

Reminds me of my then young daughter looking at a freshly mowed field one Friday night while driving to the lake. "Dad, if you want the grass to grow, why do you cut it? And if you don't want it to grow, why do you want it to rain?"

Out of the mouths of babes....

[Grant]

It's been snowing pretty well all day. Check out the other cams. Looks like it's slowed to a near stop now, though (16:44 Wednesday).

[KBoater]

Hum. a 3" tide could affect whether you hit a piece of NH Granite. I remember a 5" clearance required getting onto an island. I have a good tide program I use in FL and will set it for Portsmouth in the summer. Do you have any more info. On the size of the lake required for the tide to take effect.

[trfour]

I can't whistle either!

[upthesaukee]

At about 5 PM on Thurs 1-6, there was about 4 inches of snow on my driveway and lawn. I was glad to see the pull in my driveway about 7:30 so that I wouldn't have to except in front of the garage and front door. Had to use the roof rake on the back of the house, almost a flat roof that tends to leak if I don't keep the snow off it. Wife is betting this will be the last time we will see the grass until March or April.

[Mee-n-Mac]

While I believe that even a small body of water like Winni has tides, at least theoretically, the 3" number sounds way too large. I've seen numbers like 1" - 2" for tides on Lake Michigan. I tried to research it a bit, to see if I could find a reasonably simple way to calculate an approximate tide for Winni but alas I've not yet found one. The 2 sites below start to give an idea a to how to do it but I've yet to have time to fully comprehend them. Perhaps if it's snowing tomorrow and I break out the Brandy early, I can do a little light reading and post a result. It won't be as much fun as mcdude's snow day train thread but what can I do ...

http://www.rain.org/~mkummel/stumpers/06dec02a.html

http://www.jal.cc.il.us/~mikolajsawicki/Tides_new2.pdf

ps - is the study done by the UNH Maritime Club available online ?

[ghoti]

I agree, 3" seems a lot. I would think that people in those areas would see that the lake level at their dock varies up to three inches a couple of times a day. That would be pretty noticeable. Also, I'd wonder why there'd be a tide in just those areas. There's only so much water, and if it's up or down there, it's got to be down or up somewhere else.

[ApS]

Three inches did seem too much. Most sites say that barometric pressure and winds will counteract any tidal action on lakes.

Anyway, here's what www.thespaceguy.com says:

In addition to rivers, lakes are also affected by the lunar tide action. These are effects usually easier to detail. Lake high tides are opposite the Moon when the Moon is below the horizon. If the Moon is up, the water of the lake follows the Moon around the shore. Low tide goes along the opposing shore. Lake Michigan, for example, has a tidal difference of 1¾ inches. http://www.thespaceguy.com/moontides.htm

A finding which floored me was that scientists have determined that Jupiter's effect on Earth's tides can be measured!

I see a constant flow of the surface water passing by my dock -- always to the east -- in fair weather. What's that about? Coriolis Effect?

[Bear Islander]

If you look at the real time lake level chart you will see variations that could indicate micro tides.

But the variations within a 24 hour period are in the 0.3" to 0.5" range. If there was a 3" tide it should show up on this chart and it doesn't.

The chart is in feet, so each grid is 0.6".

[ApS]

I hate it when they show "100ths" of a foot. The metric system is messing us up.

Since this gauge passes under the Moon every day, and if this chart intends to show "microtides", at what time of day did the Moon pass over?

P.S. Yesterday, The New York Times advised that tide gauges had recorded the tsunami's effect...on Florida!

[glennsteely]

The papers here yesterday said that the tsunami's after effects also hit Atlantic City and other New Jersey beaches.....

[Bizer]

All bodies of water have tides, even your bathtub. Measuring it is another story. Lake Superior has tides of 2" and it's 340 miles long. Winnipesaukee's tides can't be 3".

Ocean tides caused by the moon are slightly more than one foot. It's the funneling and resonance effect that causes the higher tides here in New England. Using this 12" figure divided by the earth's radius and multiplying by the length of Winnipesaukee, this gives the tides here about 1/16th inch, about the thickness of a nickel. This is only 0.005 feet and is not measurable on the USGS gauge at Weirs Beach.

When it's high tide in one part of the lake, it's low tide at the other end. Both Center Harbor and Alton can't be in sync with the tides of Portsmouth. One could, but not both.

While the tide height is not noticeable, some water does move back and forth each tide cycle of 12 1/2 hours. This causes enough water movement so that water may not freeze in narrow passages, such as between islands.

Another effect causes the height to fluctuate is seiching. A strong northwest wind would blow some water from Center Harbor towards Alton. This raises the water in Alton and lowers it in Center harbor. When the wind stops, the water sloshes back and forth for a while. The effect is usuall less than an inch but it probably is what causes the fluctuations seen on the USGS graph of water height.

I see a constant flow of the surface water passing by my dock -- always to the east -- in fair weather. What's that about? Coriolis Effect?

I'm guessing here, but since the prevailing winds are from the west, it moves the surface water to the east. I assume the deeper water is moving to the west to replace it.

[Bear Islander]

Originally Posted by Bizer

While the tide height is not noticeable, some water does move back and forth each tide cycle of 12 1/2 hours. This causes enough water movement so that water may not freeze in narrow passages, such as between islands.

This must be why cars keep going through the ice at Hole In The Wall.

Thanks Bizer!

[Cal]

I have read where on the Great Lakes (perticularly Erie and Ontario)there can be as much as 1 to 2 feet changes but this is not due to a lunar cycle. A stong east or west wind can creat a mini "storm surge" at one end or the other causing the opposite end to drop

I think most of Winni's movement is due to the downhill flow of water all headed for Weirs channel and over the dam. Lake Wentworth is higher than Winni and flows into Back Bay and under the Wolfeboro bridge as does the water under the Alton Bay bridge.
Don't be fooled by the actions of the wind. It can blow a surface object against the flow of the water.
I remember as a kid watching the markers off Sandy Point in Alton Bay move (lean) one way or the other , making it appear the "tide" was moving one way or the other. Came to find out it was the result of wind and waves more than anything else

[ApS]

Originally Posted by Cal

"I have read where on the Great Lakes (perticularly Erie and Ontario)there can be as much as 1 to 2 feet changes... A stong east or west wind can creat a mini "storm surge" at one end or the other causing the opposite end to drop..."

One to two feet sounded like too much; however, Wisconsin studies show:

On enclosed water bodies, storm winds lower the water level on the upwind shore. The drop in water level is called a set-down and is similar in magnitude to the storm surge. On Lake Erie, a storm surge at Buffalo on the eastern end of the lake and the set-down on the western end of the lake have caused a water level difference of up to 15 feet.

http://www.seagrant.wisc.edu/outreac...urgeseiche.asp

New Jersey? Florida? The tsunami's "tidal" effect produced a three-foot surge in a well in western Virginia (Christianburg, specifically):
http://www.lasvegassun.com/sunbin/st...010801685.html well tsunami

BTW, hilly Christianburg, VA, reminds me of how the Winnipesaukee basin will look in twenty years. I'll take a photo of Christianburg this March. Hilly Hazelton, PA, too.

[kchace]

Originally Posted by Bear Islander

This must be why cars keep going through the ice at Hole In The Wall.

Thanks Bizer!

I believe you're right. I have personally seen a significant underwater current while going through the hole in the wall. It was churning unerwater and I could see leaf debris being carried along. I was shocked when I first saw it until I pondered it a while. If I remember correctly, the wind had recently shifted.

Ken

[camp guy]

All this talk about tides has brought up two gastronomic questions: 1), With the receding tide, at which beach will the clamming be the best, and, 2), on what tide do the stripers run. Everyone knows Winnipesaukee soft shell crabs are the best, and nothing beats a 1 1/2 to 2 pound lobster freshly caught off the end of Welch Island. On a factual, although not so serious note, I'll bet that anyone who reads this page and works around the Lake during tourist season has had someone ask, "When is high tide?" For me, this will be long winter. Happy New Year to All. Come on Ice Out.

[GWC...]

For clams of the muscles variety, they are freely available, irregardless of the tidal situation – just head for a sandbar or dock and start looking, in the water, of course. Don't forget the pasta.

Stripers? Say, that was a typo. Right? They seem to streak whenever the urge strikes, also irregardless of the tidal situation.

Oops, did you mean stripers, as in bass? Follow one of those low-rider style boats with the big outboard hanging on the stern.

As for crabs, watch the local raccoons. They seem to have crab catching mastered.

One thing is for sure, it always seemed like low tide, odor-wise, at the state park by the Long Island bridge – must be a NY thing?

Don’t you just love cabin fever?!?

[SAMIAM]

Camp and Bear Islander were the only two ,so far that questioned my tide theory....surprizing,since I was bored.in my office,that day and made the whole thing up.There is no UNH Maritime group that I know of....and inland lakes don't have a tide.I had not been into the cocktails....just a bad case of cabin fever....sorry....maybe I'll try and get some help

[Island Girl]

I am probably sticking my foot in my mouth.... When I read your post I started searching for lake tides from the great lakes and found a few references including the one below. I thought your numbers were a little large though.



"Some people are curious whether we have tides on Lake Superior. Yes, we do, but they are so small that they are not observable. About an inch of rise or fall because of the moon and sun's gravity is all that can be expected. However, we have another water lever fluctuation called a seiche (pronounced saysh), which can amount to about one foot on this lake. It is caused by atmospheric pressure (high at one end of the lake and low at the other), and by wind blowing in the right direction, which piles water up at one end of the lake, lowering it at the other. " http://bobscabins.duluth.com/geology.html

Open Seasonally
May 1st - Mid October

[kchace]

While I have no opinion about the presence of tide, the current I have seen running through the Hole In the Wall was real. I chocked it up to wind pushing the water around.

Ken

[Mee-n-Mac]

OK well the Brandy didn't flow (unlike the tides) last weekend but I'm still (marginally) on the case. Winni should have a tide (lunar, solar) but whether we could ever measure it is another question. I'm still looking for a closed form answer but if I have to, a simulation might do. Don't hold your breath (as if this warning was needed !) But let's have some fun a speculate a bit. When the moon is in the east the water should flow and stack to the east, perhaps down Alton Bay. Then as the moon comes overhead as goes west, the water should follow, leading to a tidal bore (I mean the wave, not me) going from Alton to Meredith or Center Harbor as has been seen (been there, seen that) on rivers. As the moon sets in the west the water should stack at that end of the lake waiting for the moon to cross the other side of the Earth. No doubt APS has missed this bore amongst to cruiser wakes

On a real note ... Bizer is correct. I have witnessed a wind induced "tide" of 1 -2 " at my friends dock, judged by the water height vs his docksteps (alas w/o dock spider squisher). This beats any lunar /solar tides I may have missed

Anyone have any comments on a Winni Wave-o-Meter ? In response to some discussions on wave (and wake) height I started to design a simple (?) measuring device that would record water level every 0.1 secs for a week and store the result on a flash/USB/jump drive. Alas the cost got into the $80 range which was more I figured anyone (even me) would care to pay for simple fun science experiment. Still I may finish it and make one just for giggles (I've got other more "pressing" boat electronics to do though) so if I get motivated I'll let y'all know. 8 ft waves on Winni, hmmm, perhaps we'll really find out out

[upthesaukee]

Build it, market it, and before you know it, everyone with lakeshore property will want to have an "MnM WTM" device, short for a Mee-n-Mac Winni Tide Meter.

Ah yes, I knew him before he surpassed Bill Gates in earnings!

[Mee-n-Mac]

Originally Posted by Mee-n-Mac

Winni should have a tide (lunar, solar) but whether we could ever measure it is another question.

Well I'm done thinking about it. If you read the 2'nd URL I posted above it shows a wide variance btw actual tides and simple calculations. Specifically 2.6' for a max tide (if the earth were a perfectly round ball covered in water) and yet we know actual tides are much higher (in places) due to water depth, shape of the coast and funneling. I was going to model Winni as a trench of constant depth and width, some 25 miles long and figure out a simple theoretical tide, but given the above, this model would be too simple to give any sort of answer at all. Oh well it was an interesting question anyway ...